Crocodiles
The largest species is the Indopacific Crocodile, Crocodylus porosus, which may exceed lengths of 20 feet...
by Rajesh Nandan Singh [Forwarded Email]; AIT College, Chikmagalur, Karnatak, India

The earliest crocodilians evolved over 200 million years ago. Crocodilians are usually considered to be the only living members of the Archosauria, the group which included the dinosaurs. The 23 species of alligators, crocodiles, and their kin, caiman and gharials, are collectively known as crocodilians. However, some scientists believe birds, which are the closest living relatives of crocodilians, should also be included in this group. Crocodilians play a vital role in the habitats where they are found. During times of drought, crocodilians create "wallows" or depressions in the ground, which fill with ground water and allow other animals to drink. They keep waterways open by clearing plants away when they swim. They are the top predators in their environments and help regulate populations of other animals. They break down nutrients for flora and fauna at the other end of the food chain, and the cycle starts over (insect eats plant, frog eats insect, alligator eats frog, alligator feeds plant.)

Alligators have a rounded snout, while crocodiles have a triangular snout. Alligators can tolerate colder weather than crocodiles. The fourth lower tooth can be seen when the mouth is closed. In alligators, this tooth fits into a socket in the upper jaw.

In the hot, summer months, for about 15 minutes. In the winter, from 1 to 2 hours. Reptiles' metabolic rate, food and oxygen consumption, and activity level depends on the outside temperature. The warmer the temperature, the higher the metabolism, and the colder the temperature, the lower the metabolism.

Crocodilians are opportunistic feeders- they will eat anything they can catch. Young crocodilians feed primarily on small mammals, fish, insects, and amphibians such as frogs. Adults will consume these prey as well as larger mammals, birds, and reptiles found in their range.

The average clutch or group of eggs is from 20 to 60 eggs, depending on the species. The eggs are laid into a nest. Some species, like the alligators, build a nest of soil, leaves, and other vegetation. Other species, like the Mugger Crocodile, dig a tunnel-type nest.

Mother crocodilians will guard their nests for the 70 to 100 days it takes for the eggs to hatch, and assist in hatching. Babies may stay with their mothers for up to 2 years. She protects them from predators as best she can, but they are completely able to fend for themselves.

The 8 to 10 inch hatchling may grow 2 to 12 inches per year, depending on the species. Females may take 8 to 14 years, and males 10 to 17 years to mature.

Without internally probing the animals, one way to tell is by size- adult females are smaller than adult males. Average size for females is between 6 to 8 feet, for males, 10 to 12 feet.

The largest species is the Indopacific Crocodile, Crocodylus porosus, which may exceed lengths of 20 feet. The smallest is the Dwarf Caiman, Paleosuchus palpebrosus. This species only reaches 4 to 5 feet. The record length for American Alligators is 19'2".

It is illegal to capture, molest, feed or harm alligators, or possess or buy them without permits, or disturb their nests or eggs. They do not make good pets and become dangerous as they grow larger.

The maximum speed is around 11 mph. Bursts at these speeds are used primarily for catching prey, and escaping predators.

Large alligators can be dangerous, particularly those that have been fed by people. Feeding alligators and other wild animals is not only illegal, but causes them to lose their fear of humans. They become bold, aggressive and come to expect more food, which can be dangerous to people and ultimately to the animals. A mother crocodilian protecting her nest or young is very dangerous. In the United States from 1948 to 1995, there were 236 attacks on humans by alligators, 8 of which were fatal. Each year, there are thousands of attacks and hundreds of fatalities from Nile Crocodiles in Africa, and Indopacific Crocodiles in Asia and Australia.